INTRODUCTION: Diabetic nephropathy (DN) is the major cause of chronic renal failure, and proteinuria is an independent risk factor for end stage renal disease. The random urine protein: creatinine ratio (P: C ratio) can accurately predict the amount of 24-hour urinary protein excretion. Apelin is thought to be associated with endothelial dysfunction, angiogenesis, and inflammation. This study investigated the apelin concentration and its association with the urine P: C ratio and metabolic parameters in patients with and without type 2 diabetes mellitus (T2D).METHODS: This study recruited 86 subjects; 56 with newly diagnosed and untreated T2D and 30 non-diabetic controls. All subjects underwent a complete clinical examination that included anthropometric and laboratory measurements.RESULTS: There were 24 males and 62 females in the study, and the mean age was 52.27 ± 11.34 years. There were no differences in age, TSH, creatinine clearance and apelin levels between groups. As expected, fasting plasma glucose, weight, body mass index and HbA1C were higher in T2D subjects (p=0.001, p = 0.02, p = 0.03 and p=0.001 respectively). Although apelin levels were higher in the control group, the differences were not statistically significant (p = 0.93). The P: C ratio levels were lower in the control group, and the differences were statistically significant (p = 0.006). A Spearman correlation analysis revealed that serum apelin levels were not correlated with the urine P: C ratio.

DISCUSSION AND CONCLUSION: Our study demonstrates that T2D is associated with decreased serum apelin levels and increased urine P: C ratios compared to those in non-diabetic subjects. This association may depend on impaired glucose homeostasis. Our results show the serum apelin levels were not correlated with the urine protein: creatinine ratio and provide further evidence regarding the relationship between apelin and DN.